<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Sender concepts</title>
<link rel="stylesheet" href="../../boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.75.2">
<link rel="home" href="../../index.html" title="Asio">
<link rel="up" href="../reference.html" title="Reference">
<link rel="prev" href="Scheduler.html" title="Scheduler concept">
<link rel="next" href="Service.html" title="Service requirements">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr><td valign="top"><img alt="asio C++ library" width="250" height="60" src="../../asio.png"></td></tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="Scheduler.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="Service.html"><img src="../../next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="asio.reference.Sender"></a><a class="link" href="Sender.html" title="Sender concepts">Sender concepts</a>
</h3></div></div></div>
<h5>
<a name="asio.reference.Sender.h0"></a>
        <span><a name="asio.reference.Sender.sender_and_sender_to"></a></span><a class="link" href="Sender.html#asio.reference.Sender.sender_and_sender_to">sender
        and sender_to</a>
      </h5>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">&gt;</span>
  <span class="identifier">concept</span> <span class="identifier">sender</span> <span class="special">=</span>
    <span class="identifier">move_constructible</span><span class="special">&lt;</span><span class="identifier">remove_cvref_t</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;&gt;</span> <span class="special">&amp;&amp;</span>
    <span class="special">!</span><span class="identifier">requires</span> <span class="special">{</span>
      <span class="keyword">typename</span> <span class="identifier">sender_traits</span><span class="special">&lt;</span><span class="identifier">remove_cvref_t</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;&gt;::</span><span class="identifier">__unspecialized</span><span class="special">;</span> <span class="comment">// exposition only</span>
    <span class="special">};</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">R</span><span class="special">&gt;</span>
  <span class="identifier">concept</span> <span class="identifier">sender_to</span> <span class="special">=</span>
    <span class="identifier">sender</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span>
    <span class="identifier">receiver</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span>
    <span class="identifier">requires</span> <span class="special">(</span><span class="identifier">S</span><span class="special">&amp;&amp;</span> <span class="identifier">s</span><span class="special">,</span> <span class="identifier">R</span><span class="special">&amp;&amp;</span> <span class="identifier">r</span><span class="special">)</span> <span class="special">{</span>
      <span class="identifier">execution</span><span class="special">::</span><span class="identifier">connect</span><span class="special">((</span><span class="identifier">S</span><span class="special">&amp;&amp;)</span> <span class="identifier">s</span><span class="special">,</span> <span class="special">(</span><span class="identifier">R</span><span class="special">&amp;&amp;)</span> <span class="identifier">r</span><span class="special">);</span>
    <span class="special">};</span>
</pre>
<p>
        None of these operations shall introduce data races as a result of concurrent
        invocations of those functions from different threads.
      </p>
<p>
        A sender type's destructor shall not block pending completion of the submitted
        function objects.
      </p>
<p>
        [<span class="emphasis"><em>Note:</em></span> The ability to wait for completion of submitted
        function objects may be provided by the associated execution context. —<span class="emphasis"><em>end
        note</em></span>]
      </p>
<h5>
<a name="asio.reference.Sender.h1"></a>
        <span><a name="asio.reference.Sender.typed_sender"></a></span><a class="link" href="Sender.html#asio.reference.Sender.typed_sender">typed_sender</a>
      </h5>
<p>
        A sender is <span class="bold"><strong>typed</strong></span> if it declares what types
        it sends through a receiver's channels. The <code class="computeroutput"><span class="identifier">typed_sender</span></code>
        concept is defined as:
      </p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span><span class="special">...&gt;</span> <span class="keyword">class</span> <span class="identifier">Tuple</span><span class="special">,</span> <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span><span class="special">...&gt;</span> <span class="keyword">class</span> <span class="identifier">Variant</span><span class="special">&gt;</span> <span class="keyword">class</span><span class="special">&gt;</span>
  <span class="keyword">struct</span> <span class="identifier">has</span><span class="special">-</span><span class="identifier">value</span><span class="special">-</span><span class="identifier">types</span><span class="special">;</span> <span class="comment">// exposition only</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span><span class="special">...&gt;</span> <span class="keyword">class</span> <span class="identifier">Variant</span><span class="special">&gt;</span>
  <span class="keyword">struct</span> <span class="identifier">has</span><span class="special">-</span><span class="identifier">error</span><span class="special">-</span><span class="identifier">types</span><span class="special">;</span> <span class="comment">// exposition only</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">&gt;</span>
  <span class="identifier">concept</span> <span class="identifier">has</span><span class="special">-</span><span class="identifier">sender</span><span class="special">-</span><span class="identifier">types</span> <span class="special">=</span> <span class="comment">// exposition only</span>
    <span class="identifier">requires</span> <span class="special">{</span>
      <span class="keyword">typename</span> <span class="identifier">has</span><span class="special">-</span><span class="identifier">value</span><span class="special">-</span><span class="identifier">types</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">value_types</span><span class="special">&gt;;</span>
      <span class="keyword">typename</span> <span class="identifier">has</span><span class="special">-</span><span class="identifier">error</span><span class="special">-</span><span class="identifier">types</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">::</span><span class="keyword">template</span> <span class="identifier">error_types</span><span class="special">&gt;;</span>
      <span class="keyword">typename</span> <span class="identifier">bool_constant</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">::</span><span class="identifier">sends_done</span><span class="special">&gt;;</span>
    <span class="special">};</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">&gt;</span>
  <span class="identifier">concept</span> <span class="identifier">typed_sender</span> <span class="special">=</span>
    <span class="identifier">sender</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span>
    <span class="identifier">has</span><span class="special">-</span><span class="identifier">sender</span><span class="special">-</span><span class="identifier">types</span><span class="special">&lt;</span><span class="identifier">sender_traits</span><span class="special">&lt;</span><span class="identifier">remove_cvref_t</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;&gt;&gt;;</span>
</pre>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2003-2022 Christopher M. Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="Scheduler.html"><img src="../../prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../home.png" alt="Home"></a><a accesskey="n" href="Service.html"><img src="../../next.png" alt="Next"></a>
</div>
</body>
</html>
